基于空域的水印图像几何校正和零水印算法

为了有效实现对数字图像的版权保护，提出一种通用的水印图像几何校正和零水印算法。，用两个稳定而又相距最远的图像SIFT特征点的变化估计图像所经历的旋转和缩放参数，校正之后，再用一个稳定的SIFT特征点的变化校正图像的平移变换。根据零水印特点，随机从载体图像提取特征像素与水印像素按位异或运算构造零水印。理论分析和实验结果表明，图像几何校正算法能有效恢复水印同步，使水印算法能够正确检测水印；零水印算法具有较好的安全性，比基于DWT的同类零水印算法具有更强的抗剪切、几何变换、图像处理和常规信号处理攻击的能力。

New spatial-domain based algorithm of watermarked image geometric correction and zero-watermarking

In order to achieve the copyright protection of digital image,a universal watermarked image geometric correctionand zero-watermarking method is proposed.Firstly,test image rotation and scaling parameters can be estimated by the differ-ence between the stable and the farther SIFT feature point’s coordinates of it and those of the original image.After revising,the test image translation can be corrected by the change of one stable SIFT feature point’s coordinates of it and those ofthe original image.Then,According to the zero watermark characteristic,the zero-watermarking is constructed by performingthe XOR operation on the pixel of watermark with another pixel randomly extracted from the original image.Theoretical anal-ysis and experimental results show that the watermarked image geometric correction algorithm can effectively recover water-mark synchronization,so that the watermark can be correctly detected.The zero-watermarking method has a better security per-formance,and compared with the same class zero watermarking algorithm based on DWT,it has a stronger ability of resist-ing shear,geometric distortions,image process and signal process attacks.